Smoke detection equipment



Jan. 31, 1961 P. M. PUCILL 2,969,765

SMOKE DETECTION EQUIPMENT' Filed March 11, 1958 2' Sheets-Shet 1 Inventor Peter/11212511) Puci/l Attorney Jan. 31, 1961 P. M. PUCILLQ 2,969,765

SMOKE DETECTION EQUIPMENT Filed March 11, 1958 2 Sheets-Sheet 2 /0 F49. 5. I /7/J, 1'

Inventor A Horne y United States Patent SMOKE DETECTION EQUIPMENT Peter Melburn Pucill, Chalfont St. Peter, England, assignor to Specialties Development Corporation, Belleville, N.J., a corporation of New Jersey Filed Mar. 11, 1958, Ser. No. 720,588

2 Claims. (Cl. 116-117) The present invention relates to smoke detection equipment for use in aircraft and in particular it relates to a simple visual smoke detection device of a compact construction which may be incorporated in an aircraft instrument panel.

The device to which the present invention relates is primarily intended for the detection of smoke in air samples drawn from one or more places within the pressurised space of an aircraft employing a pressurised cabin. However, it may also be used in unpressurised aircraft, if required.

Visual smoke detectors all depend on the illumination of the solid or liquid particles in smoke by a bright light so as to render them readily visible to the eye. In aircraft in flight the possibility of repairing instruments of any kind is limited and replacements must be made as simple as possible. Since the only likely component of the detector to fall is the bulb which provides the source of illumination, it is an object of the present invention to provide a means for replacing the bulb, which is located inside the detector, in a very simple way.

According to the present invention a smoke detector device comprises a casing, an observation window in the front end of the casing, an electric bulb removable through the front end of the casing, an air sample and an air sample outlet in the rear end of the casing, the bulb being screened from direct view through the window and being positioned so as to illuminate smoke particles in air drawn into the casing through the inlet.

The inlet (or each inlet, if there is more than one) is provided with an air flow indicating member, which occupies a rest position when there is no air flow and moves to a flow-indicating position when there is a flow of air. Preferably the bulb is positioned so as to illuminate the air flow indicator when in the flow-indicating position, but not in the rest position.

One construction of smoke detector made in accordance with the invention is hereinafter described with reference to the accompanying drawings wherein:

Figure 1 is a front view of the detector;

Figure 2 is a plan view of the detector;

Figure 3 is a section of the detector; and

Figure 4 is a wiring diagram.

The detector instrument is housed in a standard aircraft instrument case 1. The interior of the case is divided by a horizontal partition 2 to define a lower space in which the bulb 3, bulb holder 4 and associated wiring are housed, and an upper space. The upper space is in turn divided by a vertical partition 5 so as to define two separate chambers into which the sample air is drawn.

The bulb holder 4 is engaged with the casing by means of a bayonet fastening and can be removed complete with the bulb 3 from the casing for in flight replacement of the bulb, by giving a part turn to the bulb holder by means of a knob 6 projecting through the front of the 2,969,765 Patented Jan. 31, 1961 casing. The bulb holder 4 has a pair of bayonet pin contacts which engage with stationary contacts 7 on the rear face of the front end 8 of the casing 1 when the bulb holder is in position. The stationary contacts are in turn connected by suitable conductors to a socket in the rear end of the casing for connection to the electrical system of the aircraft.

A rectangular visor 9 is located in the upper part of the front of the casing so as to permit the interior of both the air sample chambers defined by the partition 5 to be directly viewed. The visor 9 is sloped at about 45 to prevent interference with vision by reflections off the visor. A screen 10 is arranged over the visor to prevent any internal light reflections from the top of the casing reaching it.

The floor of each air sample chamber is provided with a slit through the horizontal partition 2 and extending in the lengthwise direction of the casing to permit a narrow beam of light to shine up into each air sample chamber, as indicated in Figure 3.

Each air sample chamber is provided with an inlet connection 11, through which air enters the chamber from the aircraft pressurisation system. The inlets are formed in the back plate 12 of the casing 1, which is also provided with a single outlet connection 14 placed below the horizontal partition 2. The outlet connection 14 is connected to discharge the sample air outboard of the air craft.

It will be appreciated that the sample air is drawn down through the slits in the horizontal partition 2 so that any smoke particles therein must be immediately visible in the light beam emitted through the slit.

The slits are so arranged that the rear end of the light beams do not directly illuminate the rear end of the casing.

A light pivoted flow-indicating member 15 is arranged over each of the air inlets 11. When no air is flowing, these lie against the back plate 12 and are not illuminated. When air is flowing into the chamber through an inlet 11 the indicator 15 is swung into the light beam and becomes visible.

Disappearance of one of the flow-indicating members indicates a blockage in the associated inlet pipe which can be checked and unblocked if necessary. Disappearance of both flow-indicating members indicates either a complete failure of the air sampling system or that the bulb 3 has broken and requires replacement.

The contacts 7, which are engaged with the bulb holder 4, are connected with the contacts of a plug socket 16 through leads 17 and 18.

I claim:

1. A visual smoke detector device comprising a casing having vertical front and rear walls, a horizontal partition extending longitudinally within said casing dividing said easing into upper and lower chambers, electric lamp means detachably secured to said front wall extending therethrough into said lower chamber and adapted to be withdrawn from said lower chamber through said front wall, an air sample inlet in said rear wall above said partition, an observation window in said front wall above said partition in line with said inlet, an air sample outlet in said rear wall below said partition, said partition being provided with.a slit for directing light from said lamp means into a portion of said upper chamber spaced inwardly of said window and said inlet, and a visual air flow indicator positioned at said inlet adapted to occupy a non-illuminated position when no air is flowing through said inlet and to be deflected to an illuminated position when a normal air flow is flowing from said inlet.

'2. A"visual smoke detector device according to claim lfwherein 'aseco'nd partition"perpendicular"to said *first References Cited in the file of this patent "UNITED STATES PA'TENTS Cahusac et al. Dec. 29, 1942 Fleming June 22, 1954 Fleming Nov. 13, 1956 FOREIGN PATENTS Germany- June 12, 1931 Canada J-an. 22, 1957 

